Currently, methods and apparatuses exist for restoration in an optical communications system and priority for call setup, usually based upon the Class of Service (CoS). A disadvantage of this type of restoration in an optical communications system may be that low priority connections are maintained at the cost of disallowing higher priority connections access to bandwidth.
For many connections, an optical network can be required to provide reliability comparable to electric telephony networks, especially in the face of major network failures. Typically, the service offered is a reliable optical connection between a pair of nodes where service disruptions can be minimized by quickly re-establishing or restoring the optical connections through an alternate path. Another concern is access to the required bandwidth. As more demand is placed upon the bandwidth resources of an optical network, the effect of failed connections or delayed connections increases.
Traditionally, networks allocate bandwidth and resources for the transmission of data and assign certain priorities to data paths such as Quality of Service (QoS) and like. A user can configure the priority of the path, in order to guarantee that a certain CoS is restored more quickly than another-CoS.
Ring topologies are able to quickly restore circuits. This capability is important to provide reliable service to customers, and is particularly important in telephony applications, where failures and delays ultimately lead to customer dissatisfaction. As well, bandwidth allocated to restoration, provisioning and other functions may assume a large proportion of the available bandwidth.
Mesh technologies reduce the amount of bandwidth required for protection. Mesh technology is a point-to-point technology, with each node coupled to one or more nodes in the network. A connection may be routed through various nodes and the links connecting them. Excess capacity through a given node or link can protect several circuits, reducing the need for reserved bandwidth.
Each of the various connections on a network also have their own requirements as to bandwidth, restoration time, restoration guarantees and so on. Certain low-priority connections may have only minimum requirements, so call setup, restoration, and maintenance of that connection may only consist of waiting until sufficient bandwidth is available, allowing this service to be economically priced. At the other end of the spectrum, certain high priority connections require precedence for call setup, restoration and maintaining that connection. Other connections generally lie in the middle of the spectrum, where reasonable uptime and an economical cost is desired.
In view of the foregoing, it would be desirable to provide a technique for a priority-based call setup and restoration in an optical communications system which overcomes the above-described inadequacies and shortcomings by providing a mechanism which does not only provide swift setup and restoration time, but allows higher priority connections access to bandwidth by bumping lower priority connections, and then restoring those lower priority connections as bandwidth becomes available.